Geology is an Earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer to the study of the solid features of any terrestrial planet or natural satellite.
The word 'geology' was first used by Jean-André Deluc in 1778 and introduced as a fixed term by Horace-Bénédict de Saussure in 1779. It is derived from the Greek words 'gē' (Earth) and 'logos' (study).
Geology is essential for understanding the history of our planet, finding and managing natural resources, and mitigating natural hazards such as earthquakes and volcanoes.